Field of the Invention
The present invention relates to an image device, an image system, and a control method of the image device, in which the image device has a global electronic shutter function.
Description of the Related Art
In recent years, a global electronic shutter has been proposed in CMOS image sensors. Image devices disclosed in Japanese Patent Application Laid-open No. 2004-111590 and Japanese Patent Application Laid-open No. 2006-246450 use a global electronic shutter to avoid a distortion in an image of a subject that is moving fast.
The image device disclosed in Japanese Patent Application Laid-open No. 2004-111590 accumulates all the charges generated by photoelectric conversions in photoelectric conversion units and then transfers charges for one frame from the photoelectric conversion units to holding units at the same time in all the pixels. This realizes a global electronic shutter. In this case, in order to increase the saturation charge amount of a pixel, it is necessary to increase both the saturation charge amount of the photoelectric conversion unit and the saturation charge amount of the holding unit. However, an increase in the saturation charge amount of the photoelectric conversion unit causes an increase in the area of the photoelectric conversion unit resulting in an increased pixel size.
The image device disclosed in Japanese Patent Application Laid-open No. 2006-246450 holds charges in holding units without accumulating charges in photoelectric conversion units. Therefore, it may be possible to increase the saturation charge amount of a pixel without increasing the saturation charge amount of the photoelectric conversion unit. In this technology, however, since there is a period in which charges generated by a photoelectric conversion are unable to be accumulated, the image quality may be degraded.